Laser detection systems which are not positioned in the path of the laser beam rely on the detection of light scattered from a laser pulse or other time varying property of the laser beam as it passes through the field of view of the detection system. A serious problem associated with this method of laser detection is low signal to noise ratios caused by weak scattered laser light and by background radiation also present in the detectors field of view as the laser beam passes therethrough. In fact, the background radiation present in the field of view of the detection system may be so great as to make detection of the laser beam passing therethrough virtually impossible.
The present invention overcomes the foregoing mentioned problem and provides a detection system with a much higher signal to noise ratio than hitherto achievable.